Since I made that post, a couple of things have changed.
Most importantly, there’s updated information from the US Citizenship and Immigration Services about this. It’s not very long, so anybody with a real interest in this topic should read the “Maintaining Permanent Residence” section for themselves. I’ll just point out one thing:
You may be found to have abandoned your permanent resident status if you:
Move to another country intending to live there permanently [my emphasis]
When questions of intention arise in this context, it is not so simple that an immigration officer might ask you what you intend, you tell her/him that you don’t intend to live in the other country permanently, and they just accept your word. No, US Citizenship and Immigration Services determines this intention from your actions.
I have found a few online sources which provide some information about how this intention might be determined. See here, here and here.
The bottom line is that just as it is usually a lot of work and hassle and paperwork to initially obtain a green card, it is not a trivial thing to keep it while while living long term in another country.
This leads me to the other thing which has changed since 2005. Since learning more about the requirements for maintaining permanent residency, I decided that I couldn’t justify doing all these things to keep open the extremely slim possibility that I may one day return to live and work in the US on a long term basis. In my first year back, which was fairly difficult, it was nice to keep that option open. But things have changed, and I feel a lot more at home in Australia. I’ll definitely return to the US as a visitor. Who knows what the future holds, if I wish to work there again, I’d rather take my chances with one of the new E3 Visas for Australians.
Something I’ve learned, both from moving to the US as well as returning to Australia, is that changing countries is not easy - at least for me. In fact it becomes more difficult as you get older. Let’s say that one day I do return to the US for several years, well if that happened, I couldn’t ever see myself moving back to Australia - except for short visits. I don’t feel ready for that.